1. Field of the Invention
The present invention relates to an image processing system and an image acquisition method.
2. Description of the Related Art
Surveillance cameras are used for the purpose of crime prevention and the like. In many cases, a generally used method is to install a plurality of cameras and cause an observer in an observation room or the like to make checks by watching the monitors. An alternative method is to record camera images in advance and check them when a problem arises.
In general, there are very many cameras which an observer monitors. It is therefore difficult to reliably observe whether something unusual has happened in images. For this reason, a system which provides some support is used. In such a support system, in order to check whether someone has entered a prohibited area, some kind of image processing is performed to recognize such entrance. It is easy to construct a system which sets a given observation area in an image and detects whether someone has entered the area. Such a system can only set an area within an image. However, this image actually covers a considerably wide range.
JP-A 2006-134035 (KOKAI) discloses a method of simultaneously acquiring distance images by using a stereo camera and setting a detection area on the basis of the distances. This makes it possible to set a narrower detection area.
The method disclosed in JP-A 2006-134035 (KOKAI) can set a narrow detection area, but requires a stereo camera, resulting in a very expensive system. This system also requires a high-performance processing apparatus for image processing. In addition, it is generally cumbersome to make adjustment for the installation of a stereo camera, and hence it is not easy to change a detection area.